Maurice Hilleman’s mother died a day after he was born and his twin sister stillborn, and he said as an adult that he felt he had escaped an appointment with death. He made it his life’s work to see that others could do the same. The fruits of his labors were nine vaccines that practically every child gets, rendering formerly dreaded diseases—including often devastating ones such as mumps and rubella—practically forgotten. Offit, a vaccine researcher himself, befriended Hilleman and, during the great man’s last months, interviewed him extensively about his life and career. Those conversations form the basis of the book, but it is enriched and enlivened by the broad context of modern medical science and history, ranging across the globe and throughout time to take in a fascinating cast of hundreds.